Study Explains Evolution's Molecular Advance 477
pnewhook writes "The New York Times is reporting that 'by reconstructing ancient genes from long-extinct animals, scientists have for the first time demonstrated the step-by-step progression of how evolution created a new piece of molecular machinery by reusing and modifying existing parts. The researchers say the findings, published today in the journal Science, offer a counterargument to doubters of evolution who question how a progression of small changes could produce the intricate mechanisms found in living cells.'"
The NYT page, no registration required. (Score:2, Informative)
http://www.nytimes.com/2006/04/07/science/07evolv
The Blind Locksmith: Carl Zimmer's analysis (Score:3, Informative)
Re:Genes from extinct animals (Score:3, Informative)
I predict we can make millions selling the smaller ones to Creationist families. After all, don't they want to be closer to the original man?
I can see the ad campaign now: Get your child a pet dinosaur so they can ride them just like man did before the flood! Now you too can have a beast of the earth, just as God gave to Adam! (Discounts given to Church groups buying more than 3 pet dinos.)
Re:Create a live cell (Score:4, Informative)
However, it has been shown that many organic materials can be created in an environment similar to primordial earth. It has also been shown that many of these materials do tend to self-organize in a way that would be compatible with a cell possibly forming given enough organic material and time.
Cell wall: phospholipids, mostly being hydrophobic with one or two ends being hydrophilic tend to organize in sheets or water filled bubbles, and so could naturally form a cell wall. Amino acids do self aggragate to some extent, and a random aggregation could form a useful protein, ditto for RNA (which I believe preceded DNA evolutionarilly for a number of reasons.)
There is only one protein that would have to aggregate naturally before life as we know it could arise... ribosomes (or some suitable analog.) From there RNA could be transcribed into protein. At first most of the protein would pretty much be useless globs, untill a protein arises that can create copies of RNA. This protein could either aggregate naturally or be encoded by random chance into a strand or RNA. From there Darwinian evolution kicks in and as more beneficial RNA sequences come about that improve the transcription process and copying mechanism as well as the defense mechanisms, cellular life would not be too wild of an outcome. The progression of life would seem to be fairly slow at first, but the copying mechanism in RNA would probably be so imperfect that new variations arise very frequently, but most of those variations would likely be detrimental. Eventually better copying mechanisms arise, and eventually use of a more stable genetic material (DNA) make life blossom, expanding at a decent pace. Once some organism figured out a way to systematically capture and store energy from sunlight (or any energy source, really... thermal vents, gradiants across a thermo/chemocline etc) and a way to release that energy, then evolution can start proceeding at an exponential rate.
So, if it can be proven that a ribosome or some other RNA-Protein copying method could eventually arise from a random mix of amino acids it would greatly support the possibility of some method of abiogenesis. It does not have to be likely that this ribosome would arise in a human time scale... it could take millions or billions of years. It just has to happen eventually.
Complex hemes, carbohydrates and many other materials that are necessary for life at a complexity of ours would not be necessary to bootstrap the system from inert materials. Just some strands of RNA and something like a ribosome. Once you have those, something as complex as an RNA transcriptase could eventually arise from random permutations of RNA strands. And once you have RNA that has RNA -> RNA transcriptase encoded somewhere inside of itself and has some ribosome analogue working on it, then you have the bare bones beginning of organic life.
Reducible Complexity (Score:5, Informative)
The solution is that the original precursor gained the ability to bind a new hormone by a single point mutation, and this did not disrupt the ability of it to bind its old hormone. The new receptor then diverged and through a well known process of gene duplication, begat multiple and independently evolving molecules. One retained the function of binding the old hormone, whereas another mutated further to lose the ability to bind the old hormone and could now only bind the new hormone. Viola -- two seemingly "designed" systems out of one precursor -- evolution at its finest, and IMHO, damning evidence against the basic principle of Intelligent Design.
On a personal note, it never fails to amaze me how much people deny the intelligence of humans to figure things out... the old "just because we can't explain it now, it must have be an unexplicable force, like God." I'm sure lightning and earthquakes seemed supernatural too. Evolution is no different -- it can be dissected and explained.
Re:Why do we still care about the doubters? (Score:4, Informative)
For those of you who don't read science, I would like to add that the paper itself made no mention of ID at all. Of course, biologists are interested in evlotution of complex mechanisms for its own sake, not for the sake of convincing some young earth creationists.
However, Dr Christoph Adami, who wrote in Perspecives (basically, giving an opinion of the significance of a new finding and providing the non-specialist with a context of the paper) made the point of how fatal this finding is for the ID argument. Here we have parts that have exactly the "irreducable complexity" that ID proponents love to talk about, and now someone has managed to reconstruct their evolutionary history.
Tor
Creationist Nonsense (Score:4, Informative)
Memorize them for your next party
Re:The truth shall set you free. (Score:3, Informative)
I tend to agree with Kenneth Miller. Anyone that claims to be of faith should read his book 'Finding Darwin's God' where he attempts to bridge the gap between hard evolution and it's implications for religion.
Re:Matter of time (Score:5, Informative)
Quantum particles are associated with probability WAVES that fluctuate with time. When we say wave-particle duality we mean that the particle does NOT have a definite classical trajectory but instead a WAVE of probability associated with it that describes the positions, energies, and momentums at which the particle is most likely to be. This is called a wave function; it is a solution to Schrodinger's differential wave equation and its square is a probability curve.
Depending on your interpretation, quantum mechanics does indicate some things about reality such as there is an ONTOLOGICAL limit on what we can know for certain about objective reality such that it appears meaningless to talk about an absolute objective reality at all. That is, reality changes by being observed. However, unlike general relativity which does indeed EXPLAIN gravity by saying that gravity is identical with a curved space-time geometry, you are quite right in saying that quantum mechanics does not explain anything. Nor does particle theory or E&M explain why there are electric and magnetic forces without beginning to conjure up force-carrying particles and the like. They are currently trying to explain all these things by means of string theory.
full text of link (Score:1, Informative)
Study, in a First, Explains Evolution's Molecular Advance
By KENNETH CHANG
By reconstructing ancient genes from long-extinct animals, scientists have for the first time demonstrated the step-by-step progression of how evolution created a new piece of molecular machinery by reusing and modifying existing parts.
The researchers say the findings, published today in the journal Science, offer a counterargument to doubters of evolution who question how a progression of small changes could produce the intricate mechanisms found in living cells.
"The evolution of complexity is a longstanding issue in evolutionary biology," said Joseph W. Thornton, professor of biology at the University of Oregon and lead author of the paper. "We wanted to understand how this system evolved at the molecular level. There's no scientific controversy over whether this system evolved. The question for scientists is how it evolved, and that's what our study showed."
Charles Darwin wrote in The Origin of Species, "If it would be demonstrated that any complex organ existed which could not possibly have formed by numerous, successive, slight modifications, my theory would absolutely break down."
Discoveries like that announced this week of a fish with limblike fins have filled in the transitions between species. New molecular biology techniques let scientists begin to reconstruct how the processes inside a cell evolved over millions of years.
Dr. Thornton's experiments focused on two hormone receptors. One is a component of stress response systems. The other, while similar in shape, takes part in different biological processes, including kidney function in higher animals.
Hormones and hormone receptors are protein molecules that act like pairs of keys and locks. Hormones fit into specific receptors, and that attachment sends a signal to turn on or turn off cell functions. The matching of hormones and receptors led to the question of how new hormone-and-receptor pairs evolved, as one without the other would appear to be useless.
The researchers found the modern equivalent of the stress hormone receptor in lampreys and hagfish, two surviving jawless primitive species. The team also found two modern equivalents of the receptor in skate, a fish related to sharks.
After looking at the genes that produced them, and comparing the genes' similarities and differences among the genes, the scientists concluded that all descended from a single common gene 450 million years ago, before animals emerged from oceans onto land, before the evolution of bones.
The team recreated the ancestral receptor in the laboratory and found that it could bind to the kidney regulating hormone, aldosterone and the stress hormone, cortisol.
Thus, it turned out that the receptor for aldosterone existed before aldosterone. Aldosterone is found just in land animals, which appeared tens of millions of years later.
"It had a different function and was exploited to take part in a new complex system when the hormone came on the scene," Dr. Thornton said.
What happened was that a glitch produced two copies of the receptor gene in the animal's DNA, a not-uncommon occurrence in evolution. Then, for reasons not understood, two major mutations made one receptor sensitive just to cortisol, leading to the modern version of the stress hormone receptor. The other receptor became specialized for kidney regulation.
Dr. Thornton said the experiments showed how evolution could and did innovate functions over time. "I think this is likely to be a very common theme in how complex molecular systems evolved," he said.
Christoph Adami, a professor of life sciences at the Keck Graduate Institute in Claremont, Calif. who wrote an accompanying commentary in Science, said the research showed how evolution "takes advantage of lucky circumstances and builds upon them."
Dr. Thornton said the experiment refutes the notion of "irreducible complexity" put forward by Michael J. Behe, a prof
Re:ID = Heisenberg Uncertain Principle? (Score:3, Informative)
Ultimately, I just don't understand why this is an issue. Bottom line is we are here. If we have evolved then we are uniquely suited to our environment due to millenia of nature working on us. If we are here by ID, we are uniquely suited to our environment because somebody built us that way. It's a stupid argument, and stupid area of study.
Re:Reducible Complexity (Score:3, Informative)